OK, I am slow. After searching around here (unsuccessfully) to find instructions for how to install the addon, I only just now realize it's been here all along, in the original version of PP that I downloaded in November.
So, I turned ON the paged_archive addon. Still does nothing, no changes. After digging around some more, I guess I need to create an htaccess file from the "rewrite rules" code. Is that right? Is it true that I have NO htaccess file by default? It doesn't show up anywhere in my ftp client (Transmit), and I can't find an option to "Show all files." So I assume it's not there. I can create it and upload it, but I am hesitant in case there might be an invisible htaccess file there already, which I would overwrite and screw everything up. Any confirmation of this?